This invention concerns fuel rail assemblies used in electronic fuel injection systems for automotive vehicles.
Such systems as currently configured utilize a series of electrically operated fuel injectors, each associated with a respective intake valve (or valves) at each engine cylinder. The injectors are opened and closed under the control of signals received from an electronic controller which may be comprised of an engine management computer. This operation causes controlled volumes of fuel to be injected over a timed interval during each engine combustion cycle.
The fuel injectors are supplied with fuel under pressure by means of fuel rails, which are comprised of a hollow pipe supplied with fuel under pressure by a pump connected to the fuel tank.
Fuel rails are typically constructed of formed metal piping or injection molded plastic.
The injectors are mounted in the fuel rails at spaced locations so as to receive a flow of fuel from the associated fuel rail.
For V-6 and V-8 engines, a pair of side-by-side spaced apart fuel rail segments are provided, one segment for each bank of cylinders, the fuel rail segments connected by a crossover tube or hose connected to the rear end of each of the fuel rail segments.
The crossover hose is fitted to hose barbs projecting upwardly and laterally from each fuel rail at a point adjacent the rear ends of the fuel rails, the crossover hose arching across the intake manifold. The ends of each of the fuel rails are plugged, either with a disc brazed into the interior of metal fuel rails, or by a separately installed end cap or plug, used with molded plastic fuel rails.
The crossover hose is located near the firewall, and since it projects upwardly, is vulnerable to separation by sheet metal displaced past the top of engine if the front of the vehicle sustains substantial damage. The integral hose barbs themselves are made thinner than the fuel rail walls to maintain the flow passage cross sectional area, and hence are also vulnerable to damage.
In plastic fuel rails, the hose barbs may be required to extend at a steep upward angle since the barbs must be located on a parting line defined by mounting bracketry also molded as an integral part of the fuel rail. This steep upward angle requires that the crossover hose must be formed with defined bends to roughly conform the hose to the intake manifold contour. This need to form the hose with defined bends increases its manufacturing cost.
Even when formed with these bends, portions of the crossover hose protrude to increase its vulnerability.
The presence of the integral hose barb combined with a separate plug having a seal increases the length of the fuel rails at a point where available firewall clearance is sometimes minimal.
It is therefore the object of the present invention to provide a connection for the crossover hose between two fuel rail segments which renders the connection more compact and the hose less vulnerable to damage while minimizing the cost of the assemblage.